CrystalSpace

Public API Reference

csutil/threading/pthread_mutex.h
00001 /*
00002   Copyright (C) 2006 by Marten Svanfeldt
00003 
00004   This library is free software; you can redistribute it and/or
00005   modify it under the terms of the GNU Lesser General Public
00006   License as published by the Free Software Foundation; either
00007   version 2 of the License, or (at your option) any later version.
00008 
00009   This library is distributed in the hope that it will be useful,
00010   but WITHOUT ANY WARRANTY; without even the implied warranty of
00011   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012   Library General Public License for more details.
00013 
00014   You should have received a copy of the GNU Library General Public
00015   License along with this library; if not, write to the Free
00016   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00017 */
00018 
00019 #ifndef __CS_CSUTIL_THREADING_PTHREAD_MUTEX_H__
00020 #define __CS_CSUTIL_THREADING_PTHREAD_MUTEX_H__
00021 
00022 #ifndef DOXYGEN_RUN
00023 
00024 #include <pthread.h>
00025 
00026 namespace CS
00027 {
00028 namespace Threading
00029 {
00030 namespace Implementation
00031 {
00032   class ConditionBase;
00033 
00037   class MutexBase
00038   {
00039   public:
00040     void Initialize ()
00041     {
00042       pthread_mutex_init (&mutex, 0);
00043     }
00044 
00045     void Destroy ()
00046     {
00047       pthread_mutex_destroy (&mutex);
00048     }
00049     
00050     bool Lock ()
00051     {
00052       int status = pthread_mutex_lock (&mutex);
00053       return status == 0;
00054     }
00055 
00056     bool TryLock ()
00057     {
00058       int status = pthread_mutex_trylock (&mutex);
00059       return status == 0;
00060     }
00061 
00062     void Unlock ()
00063     {
00064       pthread_mutex_unlock (&mutex);
00065     }
00066 
00067   protected:
00068     friend class ConditionBase;
00069 
00070     pthread_mutex_t mutex;
00071   };
00072 
00073 
00077 #ifdef CS_PTHREAD_MUTEX_RECURSIVE
00078   class RecursiveMutexBase : public MutexBase
00079   {
00080   public:
00081     void Initialize ()
00082     {
00083       // Use different initialization
00084       pthread_mutexattr_t attr;
00085       pthread_mutexattr_init (&attr);
00086       pthread_mutexattr_settype (&attr, CS_PTHREAD_MUTEX_RECURSIVE);
00087       pthread_mutex_init (&mutex, &attr);
00088     }
00089   }; 
00090 #else
00091   
00092   // Recursive mutex when native recursive mutex isn't supported by pthread
00093   // Emulate it
00094   class RecursiveMutexBase : public MutexBase
00095   {
00096   public:
00097     void Initialize ()
00098     {
00099       MutexBase::Initialize ();
00100 
00101       recursionCount = 0;
00102       validID = false;
00103       pthread_cond_init (&unlockedCond, 0);
00104     }
00105 
00106     void Destroy ()
00107     {
00108       MutexBase::Destroy ();
00109       pthread_cond_destroy (&unlockedCond);
00110     }
00111 
00112     bool Lock ()
00113     {
00114       MutexBase::Lock ();
00115 
00116       pthread_t tid = pthread_self ();
00117       if (validID && pthread_equal (threadID, tid))
00118       {
00119         ++recursionCount;
00120       }
00121       else
00122       {
00123         while (validID)
00124         {
00125           pthread_cond_wait (&unlockedCond, &mutex);
00126         }
00127 
00128         threadID = tid;
00129         validID = true;
00130         recursionCount = 1;
00131       }
00132 
00133       MutexBase::Unlock ();
00134     }
00135 
00136     bool TryLock ()
00137     {
00138       bool ret = false;
00139       MutexBase::Lock ();
00140 
00141       pthread_t tid = pthread_self ();
00142       if (validID && pthread_equal (threadID, tid))
00143       {
00144         ++recursionCount;
00145         ret = true;
00146       }
00147       else if (!validID)
00148       {
00149         threadID = tid;
00150         validID = true;
00151         recursionCount = 1;
00152         ret = true;
00153       }
00154 
00155       MutexBase::Unlock ();
00156       return ret;
00157     }
00158 
00159     void Unlock ()
00160     {
00161       MutexBase::Lock ();
00162       pthread_t tid = pthread_self ();
00163       if (validID && !pthread_equal (threadID, tid))
00164       {
00165         MutexBase::Unlock ();
00166         return;
00167       }
00168 
00169       if (--recursionCount == 0)
00170       {
00171         validID = false;
00172         pthread_cond_signal (&unlockedCond);
00173       }
00174 
00175       MutexBase::Unlock ();
00176     }
00177 
00178   protected:
00179     pthread_cond_t unlockedCond;
00180     pthread_t threadID;
00181     int32 recursionCount;
00182     bool validID;
00183   };
00184 
00185 #endif
00186 
00187 } // namespace Implementation
00188 } // namespace Threading
00189 } // namespace CS
00190 
00191 #endif // DOXYGEN_RUN
00192 
00193 #endif // __CS_CSUTIL_THREADING_PTHREAD_MUTEX_H__

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